A lot of definitions have been made to define what human being really is. Referring to Aristoteles’ writings a popular one is that human is a thinking animal. In a daily conversation this could be seen as a degrading statement. How could human be some kind of animal? However there is no degrading in this totally logical and in a sense scientific and a bit philosophical defining. We can easily see that as a bodily existence we are of no difference from any other species on earth. Our bodies are made of cells. And these are composed of four base elements, e.d. C, O, H, N. Then in Aristotelian words the materia of our bodies are same as the other animals’. Difference comes from the form. But then this difference makes us only a different species, not a different being. And handling the matter in this way doesn’t necessarily mean an evolutionary approach. This is quite a simple factual thing. Then a task is waiting for us: What makes us a different being, not only a different species? The classical Aristotelian answer is also simple and easily acceptable: A thinking animal. Maybe this could be a bit more detailed, saying for example “a thinking animal” or “a thinking primate” in accordance with scientific classifications. But the essential part is clear: Thinking. But at this point, one of the most profound questions of philosophy –maybe the most profound of them- arises: What is thinking?